The present invention relates to a laser surgical probe and handpiece system and, more particularly, to a laser instrument adapted for the treatment of cataracts and similar ophthalmological surgical procedures.
The present probe defines a small-incision ophthalmology device generally intended to replace current ultrasonic phacoemulsification instruments. The probe is integrated into a handpiece system which serves, first, as a handle spaced in close proximity to the operative probe tip and, second, as a fluid and air interface system.
In this latter connection, cataract surgery results in the dislodging of nuclear lens material which must be evacuated, in turn, through a suction or aspiration port immediately adjacent the active laser tip region. As is well known, the removal of eye material and fluid, without the concurrent infusion of an equal volume of fluid, may result in the collapse or other damage to the eye. Consequently, the present probe and handpiece provides, in addition to its principal cataract dislodging function, the complementary functions of aspiration and infusion.
The use of lasers in ophthalmology is known, for example, in the treatment of retinal bleeding. This procedure involves the focusing of an argon or argon/krypton laser, generally with the aid of a slit lamp through the front of the eye, onto the retina where bleeding has been observed thereby coagulating or cauterizing such bleeding spots.
Retinal bleeding has also been treated by endophoto-coagulation, a procedure in which an optical quartz fiber, for the transmission of laser energy, is introduced into the eye through the vitreous material of the posterior chamber. This coagulation technique is generally combined with aspiration/infusion whereby diseased vitreous material is removed and replaced by an appropriate saline solution.
Lasers have also found application in the treatment of glaucoma. As recently reported and summarized in Ophthalmology (May 1990, Volume 97, No. 5), Nd:Yag laser techniques, in particular the use of contact laser probes, have immediately and significantly reduced intraocular pressure, the underlying pathology of glaucoma. Importantly, such improvements have been of a lasting nature.
A not infrequent side-effect of cataract surgery is the formation of what is commonly referred to as a "secondary cataract". Removal of "secondary cataracts" represents another ophthalmic disorder in which lasers have found application. Secondary cataracts are, in reality, the darkening of the posterior capsule or membrane which separates the lens from the vitreous fluid comprising the posterior cavity of the eye. In the healthy eye this capsule is transparent. Typically argon lasers are employed in the disintegration of this membrane material.
Except for the removal of these "secondary cataracts", lasers have not previously been utilized successfully in the treatment of the true cataract condition. Rather, conventional cataract treatment has required the surgical removal of the diseased lens, `expressed` through a comparatively large incision. More recently, the above-noted phacoemulsification procedure has been developed which breaks-up, then removes disintegrated nucleus and other lens material. Phacoemulsification, although facilitating cataract removal through a smaller incision, has been know to cause deleterious postoperative complications.
The present invention, therefore, represents the first direct and successful application of laser technology to the treatment of the cataract condition. Advantageously, the present apparatus and procedure (referred to as laser phacolysis) permits minimally invasive cataract removal, i.e. through a substantially smaller incision than that required for conventional procedures and, importantly, without various of the deleterious effects of phacoemulsification.
Laser phacolysis, however, does not utilize laser energy in its conventional surgical context, that is, as a medium for the direct cutting of tissue. Rather, laser energy is propagated in the conventional manner through an optical fiber to the probe herein described. The probe converts this optical energy into an acoustic shock wave which, in turn, causes the mechanical cutting or disintegration or the cataractous nuclear lens material.
More specifically, pulsed Nd:Yag laser energy is directed against a target spaced within a few millimeters from the distal end of the optical fiber. The target may be of planar or concave contour and is oriented at an angle to the incoming laser beam such that the angle of laser incidence is, for example, in the order of 45 degrees.
The target is preferably surrounded by a narrow diameter tubular housing which serves, first, to define an aspiration inlet channel and, second, as a shield to protect the patient as well as the surgeon against the otherwise uncontained reflection of laser energy. An orifice is provided in the distal forward end of the tubular housing through which the nuclear material may be withdrawn and evacuated from the lens. This forward end region of the housing may be pointed or sharpened to enhance dislodgement of the nuclear material. As presently understood, such dislodgement is occasioned not only through the direct action of the acoustic energy wave, but, by the micro-mechanical reciprocal oscillation of the probe, induced by the periodic pulsing of the laser.
A separate infusion passage and port is provided through which a saline or other solution may be introduced as required to replenish eye fluids aspirated during the cataract removal procedure.